Introduction

Overwhelming evidence has established obesity as a risk factor for osteoarthritis (OA) of the knee. Randomized clinical trials such as the Look AHEAD study have shown long term successful intentional weight loss with an intensive lifestyle intervention (ILI) in overweight and obese type 2 diabetics. Weight loss can also decrease knee pain in persons who have OA, but it is unknown if intentional weight loss can reduce the risk of TKR. To answer this question, data from the Look AHEAD study were examined to determine if intentional weight loss could reduce the risk of TKR.

Aim: The purpose of the study was to compare the position of the femoral guide wire for during hip resurfacing, computer navigation and an alignment device.

Materials and Methods: 26 cadaver specimens divided in 3 randomly selected groups and 25 patients were used to evaluate the position of the femoral guide wire in resurfacing hip arthroplasty. In two groups of cadavers the Computer Navigation was used to register and template the position of the implant. The position of the guide wire was compared to the one achieved using the alignment device. In the third group of cadaver specimens only the alignment device was used to implant the guide wire. Version was determined from the transversely cut sections of the cadaver specimens. Pre operative and post operative radiographs were used for analysis. In the patient group after registration and templating the guide wire was passed using the alignment device.

Results: There was no notching of the superior femoral neck in either of the groups. The mean and standard deviation of the anatomic neck-shaft angles was 124.91? ? 14.25?. The wire-shaft angle in the Navigation group was 131.46? ? 5.27? and in the alignment device group 134.08? ? 3.80?. In the navigation group the wire was in 0.85? ? 2.15? of retroversion as compared to 1.38? ? 4.19? of anteversion in Jig group. The position of the wires at the narrowest cross section of the femoral neck is shown in figure. The wire shaft angle as per navigation was 134.44(±5.55) as compared to 134.74 (±5.11).

Conclusion: The alignment device consistently positioned the wire more valgus and anteverted than Computer aided navigation. In all cases, the wire position was well within acceptable limits. Computer aided navigation does not seem to offer distinct advantages in resurfacing hip replacements.

Aim: To test the accuracy of implant positioning in using computer navigation in Resurfacing hip arthroplasty

Materials and methods: Brain Lab was used to register 13 cadavers. The component position was fine tuned to a desirable valgus angle. Wire was passed using navigation. The femoral heads were sectioned after insertion of the prosthesis. The measurements from the screen-shots and the transverse sections were analysed using AutoCad®

Results: The Brain lab Registered the femoral heads to 124.91° ± 14.25° (Range 97° −148° ) CCD. The actual neck shaft angles were 126.11° ± 5.33°. The implants were placed in an angulation’s of 131.46° ± 5.27 ° (Range 116° −137° ) and a version of −0.85° ± 2.1° this gave a valgus of 5.91° ± 13.66°. The position of the wire in the isthmus of the neck was −0.52 mm ± 0.69 mm inferior to the centre and 1.7mm ± 1.9 mm posterior to the centre on the transverse sections (n=6). The components were in 8.69° ± 4.95° (n= 6) valgus to the native neck shaft angle. In only 1 hip the femoral head implanted was of the same size as suggested by navigation, in all the rest of the hips the femoral component was of a larger size. This was because it was felt that implanting a smaller size would cause notching of the superolateral neck.

Conclusion: There is a learning curve involved for registering the femoral heads using computer navigation systems, however the navigation gives the surgeon a distinct advantage of being able to choose the point of entry, implant the prosthesis in as valgus position as possible in relation to the femoral head, translate the implant anteriorly and place the peg in the centre of the femoral neck in both the planes. The computer-aided navigation can optimise the component positioning and thereby provide excellent results.

Aim: To test the accuracy of implant positioning in using computer navigation in Resurfacing hip arthroplasty

Materials and methods: Brain Lab was used to register 13 cadavers. The component position was fine tuned to a desirable valgus angle. Wire was passed using navigation. The femoral heads were sectioned after insertion of the prosthesis. The measurements from the screenshots and the transverse sections were analysed using AutoCad

Results: The Brain lab Registered the femoral heads to 124.91° ± 14.25° (Range 97°–148° ) CCD. The actual neck shaft angles were 126.11° ± 5.33°. The implants were placed in an angulation’s of 131.46° ± 5.27 ° (Range 116° –137° ) and a version of –0.85° ± 2.1° this gave a valgus of 5.91° ± 13.66°. The position of the wire in the isthmus of the neck was –0.52 mm ± 0.69 mm inferior to the centre and 1.7mm ± 1.9 mm posterior to the centre on the transverse sections (n=6). The components were in 8.69° ± 4.95° (n= 6) valgus to the native neck shaft angle. In only 1 hip the femoral head implanted was of the same size as suggested by navigation, in all the rest of the hips the femoral component was of a larger size. This was because it was felt that implanting a smaller size would cause notching of the supero-lateral neck.

Conclusion: There is a learning curve involved for registering the femoral heads using computer navigation systems, however the navigation gives the surgeon a distinct advantage of being able to choose the point of entry, implant the prosthesis in as valgus position as possible in relation to the femoral head, translate the implant anteriorly and place the peg in the centre of the femoral neck in both the planes. The computer-aided navigation can optimise the component positioning and thereby provide excellent results.

Aim: The purpose of the study was to develop an instrument for positioning a resurfacing femoral component.

Materials and Methods: A new alignment device was developed, which references the natural anatomy of the patient and positions the implant in valgus, slight ante-version and centrally in the femoral neck.

Results: The device was used to position a resurfacing femoral component in 20 cadaveric femora (Group A) and in 15 patients (Group B). In the cadaver group, the valgus and version angles as well as the position of the component relative to the femoral neck centerline were assessed, using pre- and post-operative radiographs and transverse slices of the femoral necks along the component center line. In group A, the achieved valgus and ante-version angles were 9.95 ± 2.35 degrees and 1.87 ± 3.85 degrees, respectively. In the vertical plane, the implant was 0.50 ± 1.52 mm superior and in the horizontal plane, 0.57 ± 1.84 mm posterior to the centreline of the femoral neck. In the patient group, the valgus angle was 9.79 ± 5.38 degrees and the implant was 0.67 ± 1.27 mm inferior in the vertical plane. There was no notching in any of the cases. There was a very strong correlation between the pre op Neck Shaft angle and the postoperative valgus achieved (r =0.902)

Conclusion: The alignment device was quick and easy to use and positioned the femoral resurfacing component accurately and reproducibly referencing the native anatomy. The small size of the instrument makes it useful in minimally invasive techniques. The self-centering three-point design proved to be stable and superior to other currently available instruments.

Aim: The purpose of the study was to compare the placement of the guide wire for the femoral components in hip resurfacing, implanted using computer navigation and a new alignment device(jig).

Materials and Methods: The study was conducted on 13 cadaveric femora. Registration of the femoral head was carried out using Computer Aided Navigation system, Brainlab (BL) by the senior author. Guide wires were inserted using BL by the senior author and subsequently with the alignment device (jig) by the junior author. The junior author was blinded to the templated position and implanted the wire using the jig. In 6 femurs the implantation of the prosthesis was carried out in the position suggested by the BL and in 7 by the jig. All the femora were sectioned transversely after implantation and measurements were taken using callipers and subsequently using Autocad.

Results: There was no notching of the superior femoral neck in either of the groups. The mean and standard deviation of the anatomic neck-shaft angles was 124.91° ± 14.25°. The wire-shaft angle in the BL group was 131.46° ± 5.27° and in the jig group 134.08° ± 3.80°. In the BL group the wire was in 0.85° ± 2.15° of retroversion as compared to 1.38° ± 4.19° of anteversion in Jig group. The position of the wires at the narrowest cross section of the femoral neck is shown in figure.

Conclusion: The alignment device consistently positioned the wire more valgus and anteverted than Computer aided navigation, which was desired. In all cases, the wire position was well within acceptable limits. Computer aided navigation does not seem to offer distinct advantages in resurfacing hip replacements.

Introduction: The incidence of tuberculosis has increased by almost 30% annually in the UK. Orthopaedic surgeons are more likely to encounter patients affected with Mycobacterium tuberculosis [MTB]. We have reviewed the surgical and medical management of cases of MTB infecting prosthetic hip joints in patients without previous tuberculosis.

Report: A 59 year old Caucasian woman presented to us with apparent osteoarthritis hip. X-rays confirmed osteoarthritis but also revealed a lytic lesion in the greater trochanter and erosion of the superior cortex of the femoral neck. The patient had no prior history of exposure to tuberculosis and no evidence of pulmonary or osteoarticular tuberculosis. The patient was investigated preoperatively with blood tests, bone scan, CT scan, CT guided FNAC, and core biopsy. None of these showed any specific diagnostic features. She underwent a total hip replacement and was asymptomatic up to 15 months post-op when she presented with pain in the joint with an abscess over the gluteal region. The abscess was drained and special media culture grew MTB. We used 4-drug therapy for 12 months with retention of the prosthesis and a good functional result.

Discussion: Infected total hip replacement presents a management challenge and surgeons should have a high index of suspicion for Tuberculosis in recalcitrant infections where smears from infected joints are negative. The infection of a total hip replacement with MTB in patients without previous tuberculosis is very uncommon. Only 12 cases have been reported in a search of English language literature from 1966–2005.

We have analysed the wide variation in the management of these cases. The majority of authors in our review resected or revised the infected prosthesis. We are of the opinion that if the infection is clinically under control and the prosthesis is stable, medical treatment alone should suffice.

Introduction: Wrist injuries are common presentations at Accidents and Emergencies. Distal radius fractures are by far the most common. Scaphoid injuries constitute about 60% of carpal injuries. 35% occult wrist fractures are undiagnosed on 2nd visit radiography (50% distal radius/ulna). Moreover 30% patients with significant soft tissue injuries not diagnosed.

Aim: To compare the MRI (magnetic resonance imaging) and bone scans in the diagnosis of X-Ray negative wrist injuries. To functionally score these wrist at the end of 1-year to assess the outcome.

Materials and methods: A prospective study was done in 33 wrists that did not have a fracture wrist detectable on plain X-ray. The MRI and bone scan were done on the same day within 5-7 days after the injury. PD Fat Saturation Axial and Coronal images were undertaken with MRI. Clinical scoring was done after 1 year after the injury to assess the outcome of these injuries.

Results: We detected fractures in 10 wrists on bone scans and 8 fractures on MRI scans. There was a correlation between MRI and bone scan in 5 Cases. We noted 9% (3/33) of false positive cases with bone scan. Bone scans correlated with the site of injury in 10% of cases. 1 fracture was missed in both MRI and bone scan. MRI identified 4 significant soft tissue injuries and capsular edema in 29/33 cases, which were not identified on bone scans. MRI findings showed superior correlation than bone scans with clinical findings on re-examination, which was done following the scans. PRWE (patient rated wrist evaluation) was used to score the outcome of the wrists at the end of 1 year. The patients who had soft tissue or bony damage detected on MRI had significantly higher scores at 1 year of follow-up.

Conclusion: Though bone scan has high sensitivity in diagnosis of fracture, significant soft tissue injuries will be missed. On the other hand, MRI had a high sensitivity and specificity in diagnosis of a fracture and soft tissue injuries. MRI can differentiate between a bone edema and a fracture. MRI has a disadvantage of limited exposure. Clinicians must be aware of the limitations of both investigations. Though majority of these injuries do not active intervention apart from plaster or splinting, detection of these injuries is essential to prognosticate the outcome.